Mars Exploration Rovers Update - July 26, 2004

July 26, 2004
On sol 194, Spirit took a large microscopic imager mosaic, consisting of
34 images at multiple positions, of a target called "Sabre" on an
outcrop rock called "Wooly Patch." This was followed by a two-hour
reading by the M&#65533;ssbauer spectrometer and an overnight, seven-hour
reading by the alpha particle X-ray spectrometer.
On sol 195, the rock abrasion tool dug a surprisingly deep hole in only
two hours of grinding. The rock appears to be softer than what
scientists and engineers have seen previously in Gusev Crater. The alpha
particle X-ray spectrometer was placed in the rock abrasion tool hole at
Sabre. However, due to uncertainties in how long the arm and grinding
operations take, the sequence was terminated a few minutes too early and
a planned overnight alpha particle X-ray spectrometer integration did
not take place.
Spirit recovered the alpha particle X-ray spectrometer integration in
the sol 196 plan. The sol began with a microscopic imager mosaic of the
rock abrasion tool hole. The alpha particle X-ray spectrometer was put
back in position in the hole, and reading lasting more than six hours
was successfully performed, starting at about 4 a.m. Gusev time on sol 197.
The work on Sabre was completed with a very long, 21-hour M&#65533;ssbauer
integration, which was expected to be completed the morning of sol 198
(July 24). Before the integration was started on sol 197, a microscopic
imager mosaic was taken of "Mammoth," the next rock abrasion tool target
on Wooly Patch.
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OPPORTUNITY UPDATE: Opportunity Lives High off the Hog - sol 170-173,
July 26, 2004
Opportunity continued its exploration of "Endurance Crater" the past
five sols, and is now roughly 11 meters (about 36 feet) into the crater.
The only drive during this period was on sol 171, when the rover turned
around, backed down across the slope, then turned towards a feature
called "Razorback." Razorback is a vertical fracture in the local
bedrock that may contain sediment deposits with clues about the water
history in this area. The team's near-term plan is to follow Razorback
farther down into the crater, at least another 7 meters (about 23 feet).
Slopes at Opportunity's present location and immediately downward are in
the 15- to 20-degree range, which is a comfortable range for driving.
Despite the gentler slopes, the slip is still difficult to predict, as
evidenced by the sol 171 drive. In that series of maneuvers, the rover
slipped roughly 20 centimeters (about 8 inches) more than expected.
Opportunity ended up farther downslope than desired, with what appears
to be a broken piece of Razorback within arm's reach. The decision was
made to stay put and use the suite of science instruments on sols 173
and 174 to see if this rock, dubbed "Arnold Ziffel" (after a pig on the
TV series, "Green Acres"), was different from the surrounding bedrock.
A minor concern about a temperature sensor on the rock abrasion tool
that is functioning intermittently has been resolved. This sensor is
used to determine the starting temperature of the tool's motors, which
in turn is used to set motor control parameters. The rock abrasion tool
team plans to use a nearby temperature sensor on the arm turret for the
same purpose and is not expecting the loss of this temperature sensor to
affect the rover's ability to use the tool.
Sol Highlights:
170 - Used panoramic camera to image Razorback and "Flatland" (a clean
patch of bedrock nearby).
171 - Drive of 3.7 meters (about 12 feet). Total odometry is now 1,478
meters (just over nine-tenths of a mile). Used the miniature thermal
emission spectrometer to analyze some nearby geologic features. Took a
360-degree navigation camera mosaic.
172 - Used the panoramic camera and miniature thermal emission
spectrometer instruments to image the solar panels and the miniature
thermal emission spectrometer instrument's calibration target as part of
a continuing evaluation of dust accumulation. Turned on the rover
inertial measurement unit during the afternoon Odyssey
communication-relay pass as an experiment in support of our "teach your
dog new tricks" campaign. If the inertial measurement unit does not
adversely affect the communication, the team may be able to turn the
rover during the communication relay sessions to increase the data return.
173 - Took a two-by-two microscopic imager mosaic of Arnold Ziffel, to
be used on sol 174 (ending on July 21) for more accurate placement of
the M&#65533;ssbauer and alpha particle X-ray spectrometer instruments.

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